Blast coating and method of applying the same to tubing



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A fr0/iwf y Nov. 3o, 1965 w. J. SAFFQRD 3,220,437

BLAST GOATING AND METHOD OF APPLYING THE SAME TO TUBING Filed March 28, 1963 2 Sheets-Sheet 2 INVENTOR. VV/ ///c7/77 d Jaffa/d ATTORNEY United States Patent 3,220,437 BLAST COATING AND METHOD OF APPLYING THE SAME T TUBING William J. Salford, Houston, Tex., assigner to Zapata Lining Corporation, Houston, Tex., a corporation of Texas Filed Mar. 28, 1963, Ser. No. 268,748 2 Claims. (Cl. 13S- 148) This invention relates to so-called blast coatings for oil well tubing and the like and consists particularly in a novel, highly effective protective covering which permits normal flexing of the tubing.

Where an oil well production tubing traverse a perforated zone, the abrasive and corro-sive effects of material blown against the tubing through the perforations, due to the formation pressure, may seriously wear or damage the traversing tubing. Consequently, it is customary to provide vprotective coatings for at least the portions of the tubing which traverse the perforated zones of the well. However, such protective coverings, known as blast coatings, heretofore have required special equipment and techniques in their applications such that it has been necessary to ship sections of tubing to the coating plant for having the blast coating applied. This results in the loss of time and increased cost.

Consequently, an object of the present invention is to provide a blast coating which can be readily applied in the field without the use of special tool-s or techniques beyond the skill of field workers.

Another object is to provide a blast coating having superior shock and abrasion resistant properties.

Another object is to provide a blast coating having a rigid, body-forming sleeve sections which are highly resistant to penetrating as well as collapsing effects of sand and grit blown through adjacent perforations, yet which do not unduly restrict fiexing of the tubing.

These objects and others are attained by the protective coatings illustrated in the accompanying drawings which comprise, in general, a plurality of relatively narrow and shallow rings, preferably of plastic material, lodged upon the pipe at intervals. Encompassing the pipe and securely lodged upon these rings and radially spaced thereby from the pipe surface are ceramic sleeves arranged in abutting end-to-end relationship along the portion of the tubing which are to be protected. The outer surfaces of the sleeves are coated by a suitable abrasion resistant material, such a-s fiberglass wrapping embedded in epoxy resin or a rubber sleeve molded in position. The abutting ends of the ceramic sleeves, preferably, are provided with nesting curves and are secured together by non-setting cement which is normally sufficiently yielding to permit 'slight swivelling of the sleeves relative to each other during normal fiexing of the tubing.

In the accompanying drawings, FIG. l is a vertical section through a portion of a pair of tubing strings in an oil well and illustrating a blast coating applied to a portion of the tubing.

FIG. 2 is an enlarged vertical transverse section through one form of the invention.

FIG. 3 is a perspective view of the blast coating of FIG. 2 with portions cut away and sectioned.

FIG. 4 is a perspective, cut-away view illustrating a modified form of the blast coating.

FIG. 1 illustrates a casting 8 secured within a bore hole 9 of an oil well by cement 10 in the usual manner. Packings 11 and 12 close off the portion 13 of the well inside the casing and adjacent perforations 14 leading into a producing formation 15. A first tubing string 16 depends through and terminates slightly beneath upper packing 11 for communication with production zone 13. A second tubing string 17 extends through both packers Mice ' 11 and 12 and is shown as communicating through a second production zone 18 and perforation 19 with an oil or gas bearing formation 20. The portion of tubing 17 traversing zone 13 is shown provided with a protective covering or blast coating, generally designated 21.

The blast coating as illustrated in detail in FIGS. 2 and 3 comprises a plurality of relatively narrow and thin rings 22, 23 and 24, preferably of form-sustaining, somewhat resilient plastic material. These rings snugly fit the tubing and may be secured in position thereon by means of a suitable cement, such as epoxy resin. Alternatively, the spacer rings may be held in place by their own resilience. Rings 23, 23 and 24 may be quite small, an exemplary form of these rings being about 1/s in width and also in depth or radial dimension. Snugly received about rings 22-24 are a plurality `of sleeves 25 and 26 of ceramic material. Preferably, the sleeves are identical and the opposite ends thereof, respectively, are convexly and concavely curved, as at 28 and 29. The ceramic sleeves, conveniently, may be about 30 long and two of the rings, as 22 and 23, may be provided for supporting each ceramic sleeve, the rings being about 20 apart. Any number of the ceramic sleeves, in abutting end to end relationship, may be mounted upon the tubing so as to adequately protect the same. At the opposite ends of the serially arranged sleeves there are provided metal collars 31 and 32 secured in position by means of set screws 33 and 34 so as to maintain the sleeves firmly in position. Box and pin portions 36 and 37 of the tubing, preferably, are not covered by the blast coating so that making up of the tubing is not hindered thereby. The spacer rings are of sufficient thickness and spaced apart sufiiciently to accommodate expected liexing of the encompased tubing within each ceramic sleeve without damage thereto.

To complete protective cover as best shown in FIG. 3, there is applied about the ceramic sleeves a wrapping of fiberglass tape, as at 38, with an intervening layer of epoxy resin cement 39. Another layer 40 of epoxy resin i-s applied as an outer coating. While the ceramic sleeves are adequately resistant to both the collapsing and penetrating effect of sand and gritty particles which may be blown through the perforations, the outer wrapping serves to provide a coating which is resistant to abrasion as well as corrosive influences.

All `of the steps in assembling the blast coating with a tubing section may be easily achieved in the field and without special tools. For instance, rings 22, 23 and 24 may first be slipped over the tubing section and cemented in position thereon, if necessary. Next, the ceramic sleeves are slipped over the tubing and rings, and metal end collars 31 and 32 are secured in position with the use of a screwdriver. Finally, the outer coating layers 39, 38 and 40 may be readily applied.

The form in FIG. 4 has one or more ceramic sleeves, as 42, received about rings 43 which in turn are lodged upon tubing section 44. In this form, the fiberglass wrappings are replaced by a sheathing of rubber or other suitable elastomeric material 45. The term rubber as applied hereafter to the sheathing is intended to mean any suitable rubber or rubber-like material. In assembling the modified blast coating on the tubing, rings 43 and ceramic Isleeves 42 are mounted as before. Rubber sheeting -or tape is then applied about the sleeve and subjected to heat for molding the sheeting into a continuous rubber sheath lodged firmly in position about the sleeves. In this form, as in the first form, the ceramic sleeves pro- Vide rigid support and are adequately protective against crushing and penetrating forces normally encountered, while the rubber sheathing is resistant to sharp blows and corrosive and abrasive effects.

In addition to the facility of application of the blast coating, even in the eld, and its great durability, the protective covering can be removed from the tubing, if necessary, Without damage to the latter. This is achieved by rst cutting olf the fiberglass or rubber outer sheathing, then breaking or otherwise loosening the yceramic sleeves after removal `of end-holding collars 31 and 32. Finally, spacing rings 22, 23 and 24 or 43 may be driven or cut off the tubing. The materials and sizes of the ceramic sleeves, the spacer rings, and the outer sheathing are subject to considerable variation within the skillof experts in these particular fields. The invention may be modified in these and other respects as will occur to those skilled in the art, and the exclusive use of all modications as come within the scope of the appended claims is contemplated.

I claim:

1. The combination with a Well tubing having a part for traversing a production zone of a protective covering for said part comprising a plurality of rings lodged on the tubing in longitudinally spaced relation therealong, 20

a plurality of `sleeves of rigid, shock resistant material lodged on said rings in end-to-end abutment about said tubing, said rings being located between the end portions of said sleeves and the well tubing and the thickness and spacing of said rings from each other and the spacing of said sleeves from said tubing being adjusted to accommodate limited eXture of said tubing within each of said sleeves, and a coating of abrasive resistant material about said sleeves.

2. The combination described in claim 1 in which the abutting ends of said sleeves are provided with nesting curves to facilitate -swiveling of said sleeves relative to adjacent sleeves during exure of said tubing.

References Cited by the Examiner UNITED STATES PATENTS 276,472 4/ 1883 Rittenhouse et al. 13S-120 X 340,740 4/1886 Suhr 13S- 148 X 444,477 1/1891 Wright 138--137 663,570 12/1900 Haviland et al. 138-139 951,342 3/1910 Sherwood 13S- 148 X 3,047,025 l/1962 Davis 138--1'20 X LAVERNE D. GEIGER, Primary Examiner.

EDWARDiV. BENHAM, Examiner. 

1. THE COMBINATION WITH A WELL TUBING HAVING A PART FOR TRAVERSING A PRODUCTION ZONE OF A PROTECTIVE COVERING FOR SAID PART COMPRISING A PLURALITY OF RINGS LODGED ON THE TUBING IN LONGITUDINALLY SPACED RELATION THEREALONG, A PLURALITY OF SLEEVES OF RIGID, SHOCK RESISTANT MATERIAL LODGED ON SAID RINGS IN END-TO-END ABUTMENT ABOUT SAID, TUBING, SAID RINGS BEING LOCATED BETWEEN THE END PORTIONS OF SAID SLEEVES AND THE WELL TUBING AND THE THICKNESS AND SPACING OF SAID RINGS FROM EACH OTHER AND THE SPACING OF SAID SLEEVES FROM SAID TUBING BEING ADJUSTED TO ACCOMMODATE LIMITED FLEXTURE OF SAID TUBING WITHIN EACH OF SAID SLEEVES, AND A COATING OF ABRASIVE RESISTANT MATERIAL ABOUT SAID SLEEVES. 